Lafontaine (1998), in: Layberry et al., Butts. Can.: 236, suggested that the North American taxon philipi is a synonym of O. rosovi Kurentsov, 1970, Butts. Far East USSR: 49, key, figure 42(1), 50, fig. 44(6) ♂ genitalia, 73. However, since there are two syntypes of that taxon extant, and V. Lukhtanov (1989), Vestnik Zool. 1989(2): 33-34, considered them to represent two different species, I defer from accepting this synonymy until a lectotype has been designated.